WO2005122616A1

WO2005122616A1 - Communication terminal device, base station device, and radio communication system

Info

Publication number: WO2005122616A1
Application number: PCT/JP2005/010373
Authority: WO
Inventors: Akihiko Nishio
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2004-06-10
Filing date: 2005-06-06
Publication date: 2005-12-22
Also published as: BRPI0512001A; EP1744577B1; JP5295185B2; EP1744577A4; RU2006143658A; BRPI0512001B1; JPWO2005122616A1; RU2503142C2; CN102711233A; EP2364054B1; US8571567B2; EP1744577A1; KR101406626B1; MXPA06014150A; EP2364054A1; JP2011019263A; CN102711233B; CN1965602A; KR20070018991A; RU2382524C2

Abstract

There is disclosed a communication terminal device capable of eliminating collision of access request signals simultaneously transmitted from communication terminal devices in a local cell, preventing generation of interference signal in another cell adjacent to the local cell, and improving the throughput in the local cell. There is also disclosed a base station device for controlling the transmission power of the access permission signal so as to prevent generation of an interference signal in another cell adjacent to the local cell. In this device, a use sub-channel selection unit (206) has a correspondence table between the reception quality of the pilot signals divided into classes and the sub-channel allocated to the classes. According to the correspondence table, the use sub-channel selection unit (206) selects a sub-channel group of RACH correlated to the measurement result of the reception quality of the pilot signals reported from the reception quality measurement unit (205). One sub-channel to be used for transmission of the access request signal is selected at random from the sub-channel group selected.

Description

Specification

Communication terminal device, base station device, and wireless communication system

Technical field

The present invention relates to a radio communication system, and a communication terminal device and a base station device that constitute the system.

Background art

Conventionally, in a wireless communication system, when a communication terminal device such as a mobile phone starts wireless communication, the communication terminal device receives a pilot signal periodically transmitted from a base station device, and the reception quality is reduced. An access request signal subjected to transmission power control (OL-TPC) based on open loop based on the access request is transmitted to the base station apparatus using a random access channel (RACH). Then, when the base station apparatus receives the access request signal, the base station apparatus transmits an access permission signal to the communication terminal apparatus!

FIG. 1 schematically shows a configuration of a conventional wireless communication system. The wireless communication system shown in FIG. 1 includes a base station device 11 and a plurality of communication terminal devices 12. Further, with respect to the plurality of communication terminal apparatuses 12, the one that is located near the base station apparatus 11 and has a good reception state is referred to as a communication terminal apparatus 12-1. A terminal located near the boundary of the communication area of the base station device 11, that is, near the cell edge is referred to as a communication terminal device 12-2.

[0004] FIG. 2 shows, in chronological order, radio signals transmitted and received between the communication terminal device 12 and the base station device 11 when the communication terminal device 12 starts wireless communication. As shown in FIG. 2, first, base station apparatus 11 transmits a pilot signal with a constant power to a plurality of communication terminal apparatuses 12 using a common pilot channel (CPICH: Common Pilot Channel) in the downlink. .

[0005] Next, when receiving the pilot signal, communication terminal apparatus 12 transmits a random access channel (uplink) in the uplink using transmission power associated with the reception quality (reception power of pilot signal in CPICH in FIG. 2). An access request signal is transmitted to the base station apparatus 11 using RACH (Random Access Channel). This RACH sub channel The resources that can be used as resources, for example, timing, spreading code, subcarriers, etc., are predetermined, and the communication terminal device 12 randomly transmits one of the determined resources when transmitting the access request signal. I'm starting to choose!

[0006] Subsequently, when receiving the access request signal, base station apparatus 11 uses a forward access channel (FACH: Forward Access Channel) to transmit an access permission signal to communication terminal apparatus 12 at a fixed power. Send Subsequently, when receiving the access permission signal, the communication terminal apparatus 12 transmits the data to the base station apparatus 11 using the uplink data channel with the transmission power associated with the reception quality of the pilot signal. Send a packet. In FIG. 2, a downward arrow in each channel indicates a downlink, and an upward arrow indicates an uplink.

[0007] In addition to such a conventional technique, the communication terminal apparatus 12 first transmits a short packet called a preamble while gradually increasing the transmission power to the base station apparatus 11, and transmits the packet to the base station. A technology has been developed in which the communication terminal device 12 transmits an access request signal to the base station device 11 when the device 11 detects this preamble (for example, see Patent Document 1).

Patent Document 1: Japanese Patent Publication No. 2002-528997

Disclosure of the invention

Problems to be solved by the invention

[0008] However, in the related art as shown in FIG. 2, a plurality of communication terminal devices 12 each receive a pilot signal in CPICH simultaneously and transmit an access request signal in a sub-channel of R ACH. Therefore, there is a possibility that the plurality of communication terminal apparatuses 12 transmit access request signals on the same subchannel, and the base station apparatus 11 cannot receive those access request signals.

When base station apparatus 11 cannot receive an access request signal from communication terminal apparatus 12, an access permission signal is not transmitted from base station apparatus 11 to communication terminal apparatus 12, so that communication terminal apparatus 12 After a predetermined time has elapsed, the base station apparatus 11 determines that the previously transmitted access request signal has not been received by the base station apparatus 11, and when the predetermined back-off time has elapsed, the base station apparatus 11 Send access request signal again to . In other words, in such a conventional technique, an access request signal transmitted from a plurality of communication terminal devices 12 using RACH may not be received by the base station device due to collision, and the communication terminal device 12 may It takes time until the transmitted access request signal is received by the base station apparatus 11 to determine the power, and a predetermined back-off time is set before the communication terminal apparatus 12 retransmits the access request signal. Therefore, there is a problem that the time required for the communication terminal device 12 to start the wireless communication is prolonged, and the throughput in the wireless communication system is reduced.

[0010] Further, in such a conventional technique, since the access request signal is also transmitted a plurality of times with high power in the communication terminal apparatus 12-2 located near the cell edge, the access request signal is adjacent to the cell terminal 12-2. There is a problem that it becomes an interference signal in another cell.

[0011] Further, in such a conventional technique, when the base station apparatus 11 receives the access request signal, the position of the communication terminal apparatus 12 that transmitted the access request signal cannot be confirmed. The device 11 transmits the access permission signal transmitted using FACH at high power without controlling the transmission power so that all the communication terminal devices 12 located in the own cell can receive the access permission signal. However, similarly to the above, there is a problem that the access permission signal becomes an interference signal for other adjacent cells.

[0012] Further, according to the technology described in Patent Document 1, since communication terminal apparatus 12 transmits an access request signal to base station apparatus 11 with necessary and sufficient power obtained using a preamble, Although the problem that the access request signal transmitted from the communication terminal device 12-2 located near the cell edge becomes an interference signal with respect to another adjacent cell can be improved, the throughput is reduced due to the occurrence of the collision of the access request signal. The problem described above and the problem that the access permission signal transmitted by the base station apparatus 11 becomes an interference signal in another adjacent cell are not improved at all.

[0013] An object of the present invention is to avoid the collision of a plurality of communication terminal devices in the own cell even if the access request signals are transmitted at the same time and generate an interference signal in another cell adjacent to the own cell. A communication terminal apparatus that prevents the occurrence of interference signals in other cells adjacent to the own cell by controlling the transmission power of the access permission signal, and It is to provide. Means for solving the problem

[0014] A communication terminal apparatus according to the present invention is a communication terminal apparatus that performs wireless communication with a base station apparatus, wherein: a receiving unit that receives a pilot signal that also transmits the base station apparatus power; Measuring means for measuring the reception quality of the pilot signal, selecting means for selecting a sub-channel used for transmitting a signal to the base station apparatus according to the measurement result of the reception quality of the pilot signal, And a transmitting means for transmitting the signal to the base station apparatus.

The invention's effect

[0015] According to the present invention, even if a plurality of communication terminal devices within the own cell simultaneously transmit access request signals, the collision of them is avoided and the generation of interference signals in other cells adjacent to the own cell is avoided. This can improve the throughput in the own cell, and can control the transmission power of the access permission signal to prevent the occurrence of interference signals in other cells adjacent to the own cell.

Brief Description of Drawings

FIG. 1 is a diagram schematically showing a configuration of a wireless communication system according to a conventional technique.

FIG. 2 is a diagram showing, in chronological order, radio signals transmitted and received by a communication terminal apparatus according to a conventional technique to and from a base station apparatus at the start of communication.

FIG. 3 is a diagram schematically showing a configuration of a wireless communication system according to Embodiment 1 of the present invention.

FIG. 4 is a block diagram showing a configuration of a communication terminal device according to Embodiment 1 of the present invention.

FIG. 5 is a block diagram showing a configuration of a base station apparatus according to Embodiment 1 of the present invention.

FIG. 6 is a diagram showing an example of an allocation mode of RACH sub-channels for each group divided by pilot signal reception quality when a spreading code is used as a RACH sub-channel in Embodiment 1 of the present invention.

[FIG. 7] In Embodiment 1 of the present invention, when subcarriers in a multicarrier signal are used as RACH subchannels, a RACH subchannel for each group divided by pilot signal reception quality is used. The figure which shows the example of the aspect of channel allocation

[FIG. 8] In Embodiment 1 of the present invention, when a symbol of an OFDM signal is used as a sub-channel of RACH, each group divided by the reception quality of a pilot signal is used. Showing an example of allocation mode of RACH sub-channels

FIG. 9 is a diagram showing a correspondence between reception quality of a pilot signal and each group that divides a communication terminal device according to Embodiment 1 of the present invention.

FIG. 10 is a diagram showing a correspondence between each group of communication terminal devices and transmission power of an access permission signal according to Embodiment 1 of the present invention.

FIG. 11 is a diagram showing, in chronological order, radio signals transmitted and received by the communication terminal apparatus to / from the base station apparatus at the start of communication in Embodiment 1 of the present invention.

FIG. 12 is a diagram showing, in chronological order, radio signals transmitted and received by the communication terminal apparatus to / from the base station apparatus at the start of communication in Embodiment 1 of the present invention.

FIG. 13 is a diagram showing, in chronological order, radio signals transmitted and received by the communication terminal apparatus to and from the base station apparatus at the start of communication in Embodiment 1 of the present invention.

FIG. 14 is a block diagram showing a configuration of a base station apparatus according to Embodiment 2 of the present invention.

FIG. 15 is a diagram showing the correspondence between each group of communication terminal devices according to Embodiment 2 of the present invention and a set of a modulation scheme and a coding rate.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

However, in the embodiments, configurations having the same functions are denoted by the same reference numerals, and redundant description will be omitted.

(Embodiment 1)

FIG. 3 schematically shows a configuration of the wireless communication system according to Embodiment 1 of the present invention. The wireless communication system according to the present embodiment includes a plurality of communication terminal devices 200 and a base station device 300. In this wireless communication system, a plurality of communication terminal apparatuses 200 are divided into three classes based on the reception quality of pilot signals transmitted from the base station apparatus 300, for example, by CPICH. In the following, the better reception quality is also referred to as group 1, group 2, and group 3 in this order. Also, those belonging to group 1 are referred to as communication terminal device 200-1, those belonging to group 2 as communication terminal device 200-2, and those belonging to group 3 as communication terminal device 200-3. Therefore, the communication terminal device 200 near the cell edge in this wireless communication system belongs to group 3. The

FIG. 4 is a block diagram showing the configuration of communication terminal apparatus 200 according to Embodiment 1 of the present invention. Communication terminal apparatus 200 includes reception radio section 201, channel separation section 202, demodulation section 203, decoding section 204, reception quality measurement section 205, used subchannel selection section 206, encoding section 207, modulation section 208, subchannel allocation section 209, a transmission power control unit 211, a transmission radio unit 212, and an antenna element 213.

[0020] Reception radio section 201 receives, via antenna element 213, a pilot signal transmitted by CPICH from base station apparatus 300 described later, an access permission signal transmitted by FACH, and the like, and performs frequency conversion on the received signal. Then, predetermined reception processing such as analog-Z digital conversion is performed, and the reception signal after the reception processing is input to the channel separation section 202.

[0021] Channel separating section 202 determines the channel used for the received signal input from receiving radio section 201, and if the determined channel power is CPICH, measures the received signal, that is, the pilot signal, to receive quality measurement. Enter in part 205. On the other hand, if it is other than CPICH, that is, if it is F ACH or the like, the received signal is input to demodulation section 203.

[0022] Demodulation section 203 demodulates the received signal input from channel demultiplexing section 202 by a predetermined method, and inputs the demodulated received signal to decoding section 204.

[0023] Decoding section 204 decodes the received signal input from demodulation section 203 by a predetermined method to generate received data, and inputs the generated received data to a control section (not shown).

[0024] Reception quality measurement section 205 measures the reception quality of the pilot signal input from channel demultiplexing section 202, for example, a signal power to interference power ratio (SIR) or a reception power level. Then, the measurement result is notified to the used sub-channel selection unit 206 and the transmission power control unit 211, respectively.

[0025] The used sub-channel selection unit 206 has a "correspondence table" between the reception quality of the graduated pilot signals and the sub-channels assigned to each tier. Then, based on this correspondence table, a sub-channel group of RACH associated with the measurement result of the reception quality of the pilot signal notified from reception quality measurement section 205 is selected, and the selected One subchannel used for transmitting the request signal is randomly selected. The used subchannel selection unit 206 allocates the selected subchannel to the subchannel. Notify part 209. It should be noted that a correspondence table indicating the reception quality of the classified pilot signals and the RACH sub-channels assigned to each class will be described later.

[0026] The encoding unit 207 generates a transmission signal by encoding the transmission data to which a control unit (not shown) has also been input by a predetermined method, and inputs the generated transmission signal to the modulation unit 208.

[0027] Modulating section 208 modulates the transmission signal input from coding section 207 by a predetermined method, and inputs the modulated transmission signal to sub-channel allocation section 209.

[0028] At the start of wireless communication, sub-channel allocating section 209 transmits an access request signal to which a control section (not shown) and the like has also been input, on the R ACH sub-channel notified from use sub-channel selecting section 206. Allocate predetermined resources to Examples of the predetermined resource include a timing, a spreading code, a subcarrier in a multicarrier signal, and the like. Then, sub-channel allocating section 209 inputs an access request signal to which predetermined resources have been allocated to transmission power control section 211 at predetermined timing. Further, when the access request signal is input to the transmission power control section 211 and the access permission signal is not transmitted from the base station apparatus 300 within the predetermined time, the sub-channel allocating section 209 outputs the predetermined knock-off time. At the elapse of time, the RACH subchannel notified from use subchannel selection section 206 is again assigned to the access request signal, and the assigned access request signal is input to transmission power control section 211. On the other hand, when the access request signal is transmitted to the base station apparatus 300 within a predetermined time after the access request signal is input to the transmission power control In order to transmit the transmission signal input from modulation section 208 on the specified data channel, a predetermined resource is allocated to the transmission signal, and the transmission signal is input to transmission power control section 211 at a predetermined timing.

[0029] Transmission power control section 211 associates the access request signal or transmission signal input from sub-channel allocation section 209 with the measurement result of the reception quality of the pilot signal notified from reception quality measurement section 205. The signal is amplified so as to be power, and the amplified access request signal or transmission signal is input to transmission radio section 212.

[0030] Transmission radio section 212 performs predetermined transmission processing such as digital-Z analog conversion or frequency conversion on the access request signal or the transmission signal input from transmission power control section 211. After that, the base station apparatus 300 performs wireless transmission to the base station apparatus 300 via the antenna element 213.

FIG. 5 is a block diagram showing a configuration of base station apparatus 300 according to Embodiment 1 of the present invention. Base station apparatus 300 includes reception radio section 301, RACH detection section 302, demodulation section 303, decoding section 304, required transmission power calculation section 305, encoding section 306, modulation section 307, transmission power control section 308, and multiplexing section 309. , A transmission radio unit 311 and an antenna element 312.

[0032] Receiving radio section 301 receives, via antenna element 312, the access request signal transmitted by RACH from communication terminal apparatus 200 and the transmission signal transmitted by the data channel via antenna element 312, and performs frequency conversion on the received signal. A predetermined reception process such as analog-to-digital conversion or the like is performed, and the received signal after the reception process is input to the RACH detection unit 302.

[0033] RACH detection section 302 detects an access request signal for the reception signal input from reception radio section 301, and when the access request signal is detected, inputs the access request signal to required transmission power calculation section 305. On the other hand, if no access request signal is detected, it is determined that the received signal includes only a normal data signal, and the received signal is input to demodulation section 303.

[0034] Demodulation section 303 performs demodulation processing on the received signal input from RACH detection section 302 by a predetermined method, and inputs the demodulated received signal to decoding section 304.

[0035] Decoding section 304 decodes the reception signal input from demodulation section 303 by a predetermined method to generate reception data, and inputs the generated reception data to a control section and the like (not shown).

[0036] The required transmission power calculation section 305 determines the RACH subchannel used for the transmission of the access request signal input from the RACH detection section 302. The required transmission power calculation section 305 has a correspondence table provided in the used subchannel selection section 206, and based on the correspondence table, determines the subchannel power of the RACH determined by the pilot in the communication terminal apparatus 200. Understand the signal reception quality. Further, required transmission power calculating section 305 also has a “conversion table” in which the determined sub-channels are associated with the transmission power of the access permission signal, and using this conversion table, the determined RACH of the RACH is determined. The transmission power associated with the subchannel is calculated, and the calculated transmission power is notified to transmission power control section 308. The conversion table will be described later.

[0037] The encoding unit 306 transmits an access permission signal or transmission to which a control unit (not shown) is also input. The data is subjected to an encoding process by a predetermined method to generate a transmission signal, and the generated transmission signal is input to modulation section 307.

[0038] Modulating section 307 modulates the transmission signal input from coding section 306 by a predetermined method, and inputs the modulated transmission signal to transmission power control section 308.

Transmission power control section 308 amplifies the transmission signal input from modulation section 307 to the power notified from required transmission power calculation section 305, and inputs the amplified transmission signal to multiplexing section 309. .

[0040] Multiplexing section 309 receives a pilot signal periodically from a control section (not shown) or the like, and adds the pilot signal to the transmission signal input from transmission power control section 308 at the timing when the pilot signal is input. The transmission signal is multiplexed and the multiplexed transmission signal is input to transmission radio section 311. Note that multiplexing section 309 allows transmission radio section 311 to pass the transmission signal input from transmission power control section 308 as it is at the timing when the pilot signal is not input.

Transmission radio section 311 performs transmission processing such as digital Z-analog conversion and frequency conversion on the transmission signal input from multiplexing section 309, and transmits the transmission signal after the transmission processing via antenna element 312. Wireless transmission to the communication terminal device 200 is performed.

Next, operations of communication terminal apparatus 200 and base station apparatus 300 will be specifically described with reference to FIGS. 6 to 13.

In FIG. 6, when communication terminal apparatus 200 uses a spreading code as a resource of a sub-channel of RACH, spreading for group 1, group 2 or group 3 graded based on the reception quality of a pilot signal is shown. 4 shows a code allocation mode. In FIG. 6, two spreading codes # 1 and # 2 are assigned to group 1 having the best reception quality of the pilot signal, and three spreading codes # 3 and # 4 are assigned to group 2 having the medium reception quality. , # 5 are assigned, and the remaining spread codes # 6 to #n (n is a natural number of 10 or more) are assigned to group 3 having the worst reception quality.

Further, FIG. 7 shows that, when communication terminal apparatus 200 uses subcarriers in a multicarrier signal as resources of RACH subchannels, group 1, graded based on the reception quality of the pilot signal, The subcarrier allocation mode for group 2 or group 3 is shown. In Fig. 7, the group with the best pilot signal reception quality is shown. Group 1 is assigned two subcarriers # 1 and # 2, and Group 2 with medium reception quality is assigned three subcarriers # 3, # 4 and # 5, and the reception quality is the highest. Bad group 3 is assigned all remaining available subcarriers # 6 to #n (n is a natural number of 10 or more).

FIG. 8 shows a case where communication terminal apparatus 200 uses OFDM as a sub-channel resource of RACH.

(Orthogonal Frequency Division Multiplexing) In the case of using the symphony of a signal, an allocation mode of OFDM signal symbols to Group 1, Group 2, or Group 3, which is graded based on pilot signal reception quality, is shown. In Fig. 8, the symbols of the first two OFDM signals are assigned to Group 1 with the best reception quality of the pilot signal, and the symbols of the following three OFDM signals are assigned to Group 2 with the reception quality of medium. The received quality is the worst, and group 3 is assigned with all the remaining available OFDM signal symbols. Note that RACH subchannel resources can also be allocated as time slots specified by the communication scheme, in the same way as OFDM signal symbols.

FIG. 9 shows an example of a correspondence table provided in used sub-channel selection section 206. In this correspondence table, group 1 is when the measurement result of reception SIR as pilot signal reception quality by reception quality measurement unit 205 is 15 dB or more, group 2 is when it is 5 to 15 dB, and group 3 is when it is -3 to 5 dB. Group 3. RACH sub-channels are allocated to groups 1, 2 and 3 shown in FIG. 9 in the manner shown in FIGS. 6 to 8, respectively. Therefore, based on the correspondence table, the used sub-channel selecting section 206 allocates the pilot signal in the form shown in FIGS. 6 to 8 in accordance with the measurement result of the reception quality of the pilot signal notified from the reception quality measuring section 205. The selected RACH sub-channel is selected, and one sub-channel to be used for transmitting the neutral access request signal of the selected plurality of sub-channels is randomly selected. In the correspondence table shown in FIG. 9, the case where the reception quality measurement result of pilot signal by reception quality measurement section 205 is less than 3 dB is not associated with the shift group. This is because if the measurement result of the reception quality of the pilot signal is less than −3 dB, the propagation path condition is too poor, and even if the communication terminal device 200 transmits the access request signal, it is not received by the base station device 300. , The fear is high, This is to prevent the communication terminal device 200 from transmitting unnecessary access request signals in order to prevent the occurrence of interference signals in adjacent other cells. In this case, communication terminal apparatus 200 accesses base station apparatus 300 when the attenuation due to fading or shadowing on the propagation path recovers and the measurement result of the reception quality of the pilot signal becomes −3 dB or more. be able to.

FIG. 10 shows an example of a conversion table included in required transmission power calculating section 305. This conversion table is correlated with the correspondence table shown in FIG. 9, and assuming that the required reception SIR of the access permission signal in communication terminal apparatus 200 is OdB, the transmission power of the access permission signal in base station apparatus 300 is equal to that of the pilot signal. It is expressed in decibels based on the transmission power. Specifically, for group 1, since the measurement result of pilot signal reception quality in communication terminal device 200-1 is 15 dB or more, the reception quality of the access permission signal in communication terminal device 200-1 is OdB or more. Thus, the transmission power of the access permission signal in base station apparatus 300 is set to −15 dB based on the transmission power of the pilot signal. Similarly, for group 2, since the measurement result of the reception quality of the pilot signal in communication terminal apparatus 200-2 is 5 dB or more, the transmission power of the access permission signal in base station apparatus 300 is the transmission power of the pilot signal. Is set to 5 dB with reference to. Similarly, for group 3, since the measurement result of the reception quality of the pilot signal in communication terminal apparatus 200-3 is 3 dB or more, the transmission power of the access permission signal in base station apparatus 300 is equal to the transmission power of the pilot signal. Set to 3dB as reference.

FIG. 11 shows, in chronological order, radio signals transmitted and received by base station apparatus 300 when communication terminal apparatus 200-1 belonging to group 1 starts communication. Similarly, FIG. 12 shows a radio signal transmitted and received by the communication terminal apparatus 200-2 belonging to the group 2 to and from the base station apparatus 300 at the start of communication, and FIG. 13 shows a communication signal transmitted and received by the communication terminal apparatus 200-3 belonging to the group 3 Radio signals transmitted to and received from the base station device 300 at the start are shown in time series. 11 to 13, the received power level is used as the pilot signal reception quality. As shown in FIGS. 11 to 13, communication terminal apparatuses 200-1 to 200-3 all transmit on the access request signal transmitted by RACH and the data channel based on the measurement result of the reception quality of the pilot signal. The transmission power of the data packet to be transmitted. On the other hand, base station Device 300 determines the RACH subchannel used by communication terminal device 200, thereby indirectly grasping the measurement result of the reception quality of the pilot signal in communication terminal device 200, in other words, the communication terminal device. It is necessary to know which of the groups 1 to 3 200 belongs to and to control the transmission power of the access permission signal transmitted by FACH. Therefore, comparing FIG. 11 to FIG. 13, it can be seen from FIG. 13 that shows the communication terminal apparatus 2003 in which the transmission power S of the FACH for transmitting the access permission signal is different and the reception quality of the pilot signal is the lowest. It can be seen that the transmission power of FACH is the highest!

As described above, according to the radio communication system according to the present embodiment, communication terminal apparatus 200 classifies the measurement result of the reception quality of the pilot signal, and sets a RACH sub-channel dedicated to each class in advance. In order to select the RACH sub-channel to be used for transmitting the access request signal in accordance with the actual measurement result, the probability that a plurality of communication terminal devices 200 use the same RACH sub-channel at the same time is reduced. be able to. As a result, according to the radio communication system according to the present embodiment, the access request signal is reliably received by base station apparatus 300, and the number of retransmissions of the access request signal is reduced. Can start wireless communication in a short period of time, improve the throughput in the own cell, and suppress the occurrence of interference signals in other cells adjacent to the own cell.

Further, according to the radio communication system according to the present embodiment, base station apparatus 300 transmits necessary and sufficient transmission power according to the reception quality of the access request signal in each of communication terminal apparatuses 200-1 to 200-3. Since the access permission signal is transmitted in the cell, it is possible to suppress the access permission signal from becoming an interference signal in another cell adjacent to the own cell.

Further, according to the radio communication system according to the present embodiment, the reception quality of a pilot signal that has been graded according to the correspondence table provided in used sub-channel selecting section 206 in communication terminal apparatus 200. Because more sub-channels are assigned to the lower class (for example, group 3) than the higher class (for example, group 1) of the communication terminal 200 near the cell edge, the same RACH sub-channels are used simultaneously. Since the probability of use is reduced and the number of retransmissions of the access request signal is reduced, it is possible to effectively prevent the occurrence of interference signals in other cells adjacent to the own cell. [0052] Also, in the radio communication system according to the present embodiment, based on the correspondence table provided in sub-channel selection section 206 used in communication terminal apparatus 200, the reception quality of the pilot signal that has been graded is ranked higher. The range of the reception quality of the lower class is narrower than that of the lower class. Specifically, the range of the reception quality of group 1 is 15 dB or more, and the upper limit is 2 dB.The range of the reception quality of group 2 is 10 dB of 5 to 15 dB, and the range of the reception quality of group 3 is 3 dB to 5 dB. Of 8dB. Therefore, according to the wireless communication system according to the present embodiment, the lower the lower the class of the reception quality of the pilot signal, the more subchannels are allocated! Since the number of retransmissions of the access request signal of communication terminal apparatus 200 can be reduced more effectively, it is possible to more effectively prevent the occurrence of interference signals in other cells adjacent to the own cell.

[0053] The present embodiment may be modified or applied as follows.

In base station apparatus 300 according to the present embodiment, required transmission power calculating section 305 determines the RACH sub-channel used for transmitting the access request signal, and determines the transmission associated with the determined sub-channel. The case where power is notified to transmission power control section 308 has been described, but the present invention is not limited to this case. For example, required transmission power calculating section 305 measures a request signal for measuring reception quality of an access request signal. And comparing the reception quality measured by the request signal measurement section with the required reception quality in the communication terminal apparatus 200, that is, the target reception quality in the transmission power control, and determining the difference between the reception qualities. If the transmission power is larger than the value, the transmission power associated with the RACH subchannel may be increased or decreased, and the increased or decreased transmission power may be notified to the transmission power control unit 308.

Since the required transmission power calculation section 305 calculates the transmission power of the access permission signal by a closed loop based on the reception quality of the access request signal, the communication terminal apparatus 200 also performs access to the pilot signal reception power. When it takes time to transmit the request signal, or when the propagation path condition changes rapidly, the closed loop calculation of the transmission power accurately reflects the actual propagation path condition in the calculated transmission power. It may not be done. Therefore, if the required transmission power calculation section 305 calculates the transmission power by an open loop that measures the reception quality of the access request signal in addition to the calculation of the transmission power by the closed loop, the transmission power of the access permission signal is obtained. One control Layers can be done accurately.

(Embodiment 2)

Embodiment 2 of the present invention describes a case where the base station apparatus adaptively changes the coding rate and the modulation scheme for the FACH based on the resources used by the RACH. Note that the configuration of the communication terminal apparatus according to the present embodiment is the same as that of FIG. 4 and will be described with reference to FIG.

FIG. 14 is a block diagram showing a configuration of base station apparatus 400 according to Embodiment 2 of the present invention. Base station apparatus 400 includes reception radio section 301, RACH detection section 302, demodulation section 303, decoding section 304, adaptive control section 413, coding section 406, modulation section 407, multiplexing section 309, transmission radio section 311, and antenna element. 312 is provided.

[0058] Adaptive control section 413 determines, for the access request signal input from RACH detection section 302, the RACH subchannel used for the transmission, and determines the determined subchannel and the transmission parameter of the access permission signal, that is, The modulation scheme and the coding rate are set using a conversion table in which the modulation scheme and the coding rate set are associated with each other, and the set modulation scheme and the coding rate are set by the coding section 406 and the modulation section 407. To enter.

[0059] The encoding unit 406 responds to an access permission signal or transmission data, which is also input by a control unit (not shown), with transmission parameters (coding rate and modulation scheme information) input from the adaptive control unit 413. A transmission signal is generated by performing an encoding process using an encoding rate or an encoding method according to the following formula, and the generated transmission signal is input to the modulation section 407.

[0060] Modulating section 407 modulates the transmission signal input from encoding section 406 by a modulation method according to the transmission parameter input from adaptive control section 413, and inputs the modulated transmission signal to multiplexing section 309. .

FIG. 15 shows an example of a conversion table included in adaptive control section 413. This conversion table has a correlation with the correspondence table shown in FIG. 9, and the higher the reception quality in communication terminal apparatus 200 is, the higher the modulation level and the coding ratio are. For example, in group 1, the reception quality is 15 dB or more, so the required SIR is 15 dB. , R = 3Z4, and in group 2, the received SIR is 5 dB to 15 dB, so the required SIR Use QPSK, R = 1/2, for the transmission parameter where is 5 dB. The same is true for Group 3.

[0062] As the transmission parameters have higher transmission efficiency, the base station apparatus 400 can complete the transmission of the access permission signal in a shorter time.

As described above, according to the present embodiment, base station apparatus 400 can receive with a sufficiently low error rate according to the reception quality of the access request signal in each of communication terminal apparatuses 200-1 to 200-3. Since the transmission permission is transmitted using the transmission parameters with the highest transmission efficiency, the transmission time of the access permission signal can be shortened, and the access permission signal does not become an interference signal in other cells. Can be.

[0064] In each of the above embodiments, the case where the present invention is configured by hardware has been described as an example. However, the present invention can also be realized by software.

[0065] Each functional block used in the description of each of the above embodiments is typically implemented as an LSI that is an integrated circuit. These may be individually formed into one chip, or one chip may be included so as to include a part or all of them. Here, ICs, system LSIs, super LSIs, and ultra LSIs are sometimes called depending on the degree of integration of the LSI.

Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. After manufacturing the LSI, a programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Furthermore, if an integrated circuit technology that replaces the LSI appears due to the advancement of the semiconductor technology or another technology derived therefrom, the technology may be used to integrate the functional blocks. Biotechnology can be applied.

In the wireless communication system according to each of the above embodiments, a case has been described where the plurality of communication terminal devices 200 are divided into three groups in accordance with the grade of the reception quality of the pilot signal. The invention is not limited to this case. For example, the number of groups may be further increased.

[0069] Also, for example, in the 3GPP standard, the access permission signal is an AICH (Acknowledge Indicator).

Channel) ^ FACH (Forward Access and hannel), s—C and P and H (¾econdarv— and ommon Co nControl Physical Channel) ^ HS-High Speed-Shared Control Channel (SCCH) ^ Transmission may be performed using DPC H (Dedicated Physical Channel).

In each of the above embodiments, an access request by RACH and an access permission by FACH are performed, and then, a power RACH described as transmitting a data packet is used for an access request signal, and FACH is used for other than an access permission signal. A similar effect can be obtained even when used for data transmission. For example, for a short packet or a packet with a strict delay requirement, the uplink data packet is transmitted by RACH and the downlink data packet is transmitted by FACH.

Further, the RACH in each of the above embodiments may be any other contention channel as long as resources individual to the user are not allocated.

Further, in the above embodiment, the description has been given assuming that the reception quality is estimated from the reception SIR. However, the reception SNR, the reception CIR, the reception SINR, the reception CINR, the reception power, the interference power, the It may be estimated from the set error rate, throughput, MCS (combination of modulation scheme and coding rate) that can achieve a predetermined error rate, and the like. Further, the base station apparatus may be expressed as Node B, and the communication terminal apparatus may be expressed as UE.

[0073] A first aspect of the present invention is a communication terminal apparatus that performs wireless communication with a base station apparatus, wherein the receiving means receives a pilot signal to which the base station apparatus power is also transmitted, and the received pilot signal Measuring means for measuring signal reception quality; selecting means for selecting a sub-channel used for transmitting a signal to the base station apparatus according to a measurement result of the reception quality of the pilot signal; Transmission means for transmitting the signal to the base station device using a channel.

[0074] A second aspect of the present invention is the communication terminal device according to the above invention, wherein the transmitting means transmits the signal using a random access channel.

[0075] A third aspect of the present invention is the communication terminal device according to the above invention, wherein the transmitting means transmits an access request signal.

[0076] In a fourth aspect of the present invention, the selecting means allocates more sub-channels to a lower class than a higher class of the graded reception quality, and adds the number of sub-channels to a measurement result of the pilot signal reception quality. The base station from among the sub-channels assigned to the corresponding class This is a communication terminal device for selecting a subchannel used for transmitting a signal to the device.

[0077] In a fifth aspect of the present invention, in the above-mentioned invention, in the above-mentioned invention, the selecting means narrows the range of the reception quality of the lower grades from the upper grades for the graded reception quality and allocates the sub-channel to each grade. In addition, the present invention is a communication terminal device that selects a subchannel used for transmitting a signal to the base station device from subchannels assigned to a class corresponding to a measurement result of the reception quality of the pilot signal.

[0078] A sixth aspect of the present invention is to perform wireless communication with a communication terminal apparatus, wherein receiving means for receiving a signal transmitted from the communication terminal apparatus, and transmission of the received signal, The communication terminal according to detection means for detecting a used sub-channel, and transmission power associated with the detected sub-channel, or modulation scheme and coding rate associated with the detected sub-channel. And a transmitting means for transmitting a signal to the device.

[0079] A seventh aspect of the present invention is the base station device according to the above invention, wherein the transmitting means transmits an access permission signal.

[0080] An eighth aspect of the present invention is the invention according to the above invention, further comprising request signal measuring means for measuring reception quality of a signal received by the receiving means, wherein the transmitting means is provided by the request signal measuring means. In accordance with the difference between the measured reception quality and the target reception quality in the transmission power control, the transmission power associated with the sub-channel detected by the detection means is increased or decreased, and the communication power is increased or decreased by the increased or reduced transmission power. A base station device that transmits signals to terminal devices.

[0081] A ninth aspect of the present invention is the base station device according to the invention, wherein the receiving means receives a signal transmitted using a random access channel.

[0082] A tenth aspect of the present invention is configured to include a communication terminal device and a base station device, wherein the communication terminal device receives a pilot signal to which the base station device power is also transmitted, Measuring means for measuring the reception quality of the received pilot signal; selecting means for selecting a sub-channel used for transmitting a signal to the base station apparatus according to a measurement result of the reception quality of the pilot signal; Terminal-side transmitting means for transmitting the signal to the base station device using the selected sub-channel, The apparatus includes: a base station-side receiving unit that receives the signal transmitted from the communication terminal device; a detecting unit that detects a sub-channel used for transmitting the received signal; and And a base station-side transmitting means for transmitting a signal to the communication terminal device with the associated transmission power.

[0083] An eleventh aspect of the present invention is the wireless communication system according to the above invention, wherein the terminal-side transmitting means transmits an access request signal.

[0084] A twelfth aspect of the present invention is the wireless communication system according to the above invention, wherein the base station side transmitting means transmits an access permission signal.

[0085] The present specification is based on Japanese Patent Application No. 2004-173017 filed on June 10, 2004.

All this content is included here.

Industrial applicability

[0086] The communication terminal apparatus and the base station apparatus according to the present invention prevent the occurrence of interference signals in other cells adjacent to the own cell by reducing the occurrence rate of collision of an access request signal in the own cell, In addition, it has the effect of improving the throughput in its own cell, and is useful for wireless communication systems and the like.

Claims

The scope of the claims

[1] A communication terminal device that performs wireless communication with a base station device,

Receiving means for receiving a pilot signal transmitted from the base station apparatus; measuring means for measuring reception quality of the received pilot signal;

Selecting means for selecting a sub-channel used for transmitting a signal to the base station apparatus according to a measurement result of reception quality of the pilot signal;

Transmitting means for transmitting the signal to the base station device using the selected sub-channel.

[2] The communication terminal device according to [1], wherein the transmitting means transmits the signal using a random access channel.

3. The communication terminal device according to claim 1, wherein the transmitting unit transmits an access request signal.

[4] The selection means allocates more sub-channels to lower ranks than higher ranks of the graded reception quality, and is assigned to a rank corresponding to the measurement result of the reception quality of the pilot signal. 2. The communication terminal device according to claim 1, wherein a sub-channel used for transmitting a signal to the base station device is selected from the sub-channels.

[5] The selection means may further reduce the range of the reception quality of the lower class than the higher class, allocate subchannels to each class, and adjust the reception quality of the pilot signal. The communication terminal device according to claim 1, wherein a sub-channel used for transmitting a signal to the base station device is selected from sub-channels assigned to a class corresponding to the measurement result.

[6] A base station device that performs wireless communication with a communication terminal device,

Receiving means for receiving a signal transmitted from the communication terminal device,

Detecting means for detecting a sub-channel used for transmitting the received signal; transmission power associated with the detected sub-channel, or modulation scheme and code associated with the detected sub-channel And a transmitting means for transmitting a signal to the communication terminal device according to the activation rate.

7. The base station apparatus according to claim 6, wherein the transmitting unit transmits an access permission signal.

[8] Request signal measuring means for measuring the reception quality of the signal received by the receiving means Comprising

The transmitting means transmits the transmission power associated with the sub-channel detected by the detecting means in accordance with a difference between the reception quality measured by the request signal measuring means and a target reception quality in the transmission power control. 7. The base station apparatus according to claim 6, wherein the base station apparatus increases / decreases the transmission power and transmits a signal to the communication terminal apparatus with the increased / decreased transmission power.

9. The base station apparatus according to claim 6, wherein the receiving unit receives a signal transmitted using a random access channel.

[10] A wireless communication system including a communication terminal device and a base station device, wherein the communication terminal device includes:

Terminal-side receiving means for receiving a pilot signal transmitted from the base station apparatus; measuring means for measuring reception quality of the received pilot signal; and the base station according to a measurement result of reception quality of the pilot signal. Selecting means for selecting a sub-channel used for transmitting a signal to the station device;

Terminal-side transmitting means for transmitting the signal to the base station device using the selected sub-channel;

With

The base station device,

Base station-side receiving means for receiving the signal transmitted from the communication terminal device; detecting means for detecting a sub-channel used for transmitting the received signal; and a detecting means associated with the detected sub-channel. Base station-side transmitting means for transmitting a signal to the communication terminal device with the transmitted power,

A wireless communication system comprising:

11. The wireless communication system according to claim 10, wherein the terminal-side transmitting unit transmits an access request signal.

12. The wireless communication system according to claim 10, wherein said base station side transmitting means transmits an access permission signal.